鸡血石相似品种中的粘土矿物

Clay Mineral in Similar Variety of Chicken-Blood Stone

  • 摘要: 近年来,中国宝玉石市场中出现产自西安、贵州、云南、四川等地的与鸡血石外观相似的玉石品种,这些与鸡血石相似的品种中"血"为辰砂,其"地"的主要矿物组成为石英及碳酸盐矿物(方解石、白云石)。本文选取具有代表性的鸡血石相似品种样品,采用X射线粉末衍射、红外吸收光谱、扫描电子显微镜对其的矿物组成、红外光谱特征以及微区形貌特征进行测试研究。结果显示,与鸡血石相似的一些品种样品中除含辰砂、石英及碳酸盐矿物外,还含有少量的粘土矿物,包括伊利石、绿泥石、高岭石等,在红外光谱官能团区表现出粘土矿物OH振动引起的吸收峰;扫描电子显微镜下,产自西安的鸡血石相似样品中可见呈细小鳞片状的伊利石。与鸡血石相似的品种样品中少量粘土矿物,或为成矿早期少量富铝硅酸盐矿物被低温热液交代或风化而成。由于与鸡血石相似的品种中存在粘土矿物,因此鸡血石的鉴别不能简单依靠是否含有粘土矿物来进行。

     

    Abstract: In recent years, jade variety produced in Xi'an, Guizhou, Yunnan, Sichuan and other places with similar appearance to chicken-blood stone have appeared in the gem market. The "blood" colour part of those similar variety of chicken-blood stone is cinnabar and the main mineral components of base ("di") are quartz and carbonate minerals (calcite and dolomite).In this study, in order to analyze the mineral component, infrared spectra, and micro-morphology, selected representative samples of the similar varieties of chicken-blood stones were studied by using X-ray powder diffraction spectrometer (XRD), infrared spectrometer (IR), and scanning electron microscopy (SEM). Test results show that in addition to the cinnabar, quartz and carbonate mineral, those similar varieties of chicken-blood stones also contain trace amount of clay minerals, including illite, chlorite, and kaolinite.The functional area of infrared spectra shows the absorption peak of clay mineral caused by OH vibration. According to the SEM testing results, the small scaly illite was observed in the sample from Xi'an. Trace amount of clay minerals in the similar varieties of chicken-blood stone may be formed by the small amount of silicate minerals rich in aluminum which exist in early mineralization, and were metasomatized by low-temperature hydrothermal fluids or weathered. Because there are clay minerals in the similar species of chicken-blood stones, the identification of chicken-blood stone can not simply depend on whether it contains clay minerals.

     

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